Abstract

Introduction: Bonding is the primary method of attaching brackets to teeth in modem orthodontics. Thus, many studies have focused on the maximum shear bond strength values of orthodontic adhesives. In contrast, very little research has been performed considering the work of fracture of orthodontic bonding systems. Work of Fracture is defined as the area under the curve of a stress-strain graph. Previous shear bond strength studies measured the force necessary to produce bond failure. The purpose of this study was to measure the maximum shear force and displacement of six bonding systems and to calculate the work of fracture.

Materials and Methods: One hundred and eighty bovine teeth were collected. Half of the teeth were direct bonded with titanium brackets and the other half with stainless steel brackets. Each bracket was divided into three groups of thirty and each group bonded with one of the following adhesives, Gren Gloo, Transbond XT or Glass lonomer. After bonding, the specimens were stored in distilled water at room temperature for 72 hours. The brackets were then debonded with a high-resolution tensile testing device and then assigned an Adhesive Remnant Index score.

Results: Titanium and stainless steel brackets bonded with Gren Gloo and stainless steel brackets bonded with Transbond XT had the highest and statistically equal shear bond strengths (p > 0.05). Titanium and stainless steel brackets bonded with Gren Gloo and stainless steel brackets bonded with Transbond XT had the greatest and statistically equal displacement (p > 0.05). The analyses of the six combinations of brackets and adhesives showed that titanium brackets bonded with Gren Gloo bad the highest Work of Fracture (p < 0.001). These tests showed that the brackets bonded with Fuji Ortho LC Glass lonomer, independent of bracket type, had a significantly lower Adhesive Remnant Index than those brackets bonded with Green[sic] Gloo and Transbond XT (p < 0.001).

Conclusions: Evaluating a bonding system's displacement and shear bond strength as well as calculating the work of fracture may provide more meaningful results than maximum shear bond strength alone. The combination of more resilient brackets and adhesives could lead to a significant decrease in bond failure rates. When more resilient brackets (titanium) were combined with more resilient adhesives (Gren Gloo), at least a 23.8 percent increase in the work of fracture was achieved. These laboratory findings warrant further clinical testing.

LLU Discipline

Orthodontics and Dentofacial Orthopedics

Department

Dentistry

School

Graduate Studies

First Advisor

V. Leroy Leggitt

Second Advisor

Craig Andreiko

Third Advisor

Joseph Caruso

Fourth Advisor

Dan Flores

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

2009

Date (Title Page)

9-2009

Language

English

Library of Congress/MESH Subject Headings

Orthodontics Appliances, Removable; Accident Prevention

Type

Thesis

Page Count

iv; 39

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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